Vulcanization of rubber



Patented Sept. 6, 1932 UNITED- STATES PATENT OFFICE] LAURENCE A. EDLAND, OF NORWALK, CONNECTICUT, ASSIGNOR T R. '1. VANDERBILT COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK I 'VULGANIZA'IION OF RUBBER No Drawing.

This invention relates to an improved method of Vulcanizing rubber and includes both the method and the new rubber products.

According to this invention tellurium an sulfur and an organic accelerator are employed in the vulcanization of rubber. The rubber mix may be milled on the rolls in the usual way. The use of high temperatures is not necessary and good cures can be efiected in a short time at or below 160 C., for example at forty pounds steam pressure, 1. P;

141 (1., or at fifty pounds pressure, 1. e.'148 C. The new vulcanized rubber produced by this new process is characterized by its good aging qualities and freedom from bloom.

In vulcanizing rubber according to the process of this invention, I use a small per- 0 centage of tellurium, for example not over 2%, together with a small percentage of sulfur, for example not over 2%, and an organic accelerator, and-I haveobtained excellent cures at temperatures not over 148 (1., in from fifteen to forty-five minutes. The tellurium and sulfur may be added separate ly or they may be added in combination as tellurium sulfide. I prefer to use sulfurbearing accelerators such as mercaptobenzothiazole, tetramethylthiuram disulfide, and the compounds of selenium or tellurium with dithio acids such as tellurium diethyldithiocarbamate. Sulfur-free accelerators which have given good results include diphenylguanidine, a condensation product of acetaldehyde and aniline known as ethlidene aniline, hexamethylenetetramine, and a condensation product of methylamine and formaldehyde (referred to below as trimene). However, the results with sulfur-free accelerators are generally inferior to' those with sulfur-bear- #3 ing accelerators.

Application filed March 29, 1930. Serial No. 440,174.

In making each of the cures recorded be Examples 9-20 where fifty pounds steam pressure, i. e. 148 C., was employed. Each sample was tested for tensile strength at 500% elongation; (2) tensile strength at break; and (3.) elongation at break, and in each case the results obtained are recorded in this order.

Examples 1-4 show the results obtained with and without tellurium using different percentages of crystalline sulfur and a sulfur-bearing accelerator. Examples 5-8 show the results obtained with different sulfurbearing accelerators. Examples 9-20 give comparative results with and Without tellu-' riunr using various accelerators including sulfur-free accelerators. Examples 21-25 show the results obtained by varying the amount of cystalline sulfur used.

Formula t1 #2 #3 Smoked sheets 100 100 100 100 Zinc oxide 5 5 5 5 Steeric acid 2 2 2 2 Mercaptobenzothiazolel 1 1 1 Sulfur $4 2 2 Tellurium 2 2 Cured in slab mold at 1,0 lbs. (141 (7.) for time indicated Formula 15 Minutes 30 Minutes Under-cure Undercure Uudercure 120 1680 890 Undercure 80 530 970 390 890 120 1460 850 Formula 45 Minutes Minutes Undercure 75 460 830 145 1810 890 150 2350 910 115 1300 960 160 1890 160 1850v 870 240 2610 O'ured in slab mold at 40 lbs. (1!; 0.) for time Cured in slab mold at lbs. (148 C.) for time iudicated0ontinued indicated0ontinued Formula #5 #6 I #1 #8 Formula #21 #22 #23 #24 #25 Smoked sheets. 50 5o 50 50 Smoked sheets 50 50 50 50 50 Pale crepe--." 50 50 50 50 50 50 5O 60 Zinc oxide. 5 5 5 5 5 5 5 5 5 Stearic acid. 2 2 2 2 Mercaptobenzothmzolm 1 1 1 1 1 ulfur 1% 1% 1 5 1% Stearic acid 2 2 2 2 2 Tellurium 1 1 1 1' Tellurium- 2 2 2 2 1 Mercaptobenzothiazole 1 Sullun 25 5 1 2 2 Me2N.CS.S.S.OS.NMe2 (Et2N.CSS)4Se I (Elm-053% Cured in slab mold at 141 0. for time indicated Cured m slab mold at 141 0. for time indicated Formula 5 Minutes 10 Minutes Undercure 410 900 280 2920 805 520 3800 750 Formula 15 Minutes 30 Minutes 45 Minutes Formula #9 #10 #11 #12 #13 #14 Smoked sheets 100 100 100 100 100 100 Zinc oxide 5 5 5 6 5 5 Stearic acid. 1 1 1 1 1 1 Tellurium 1 1 1 Sulfur 1.5 1 5 1 5 1.5 1.5 1 5 Mercaptobenzothiazole. 1 1 1. Me:N.OS.S.S.CS.NMe2 .25 25 Diphenylguauidiue 1. 5 1. 5

Formula #15 #16 #17 #18 #19 #20 Smoked sheets 100 100 100 100 100 100 Zinc oxide"; 5 5 5 5 5 5 Stearic acid 1 1 1 1 1 1 Tellurium. 1 1 Sul[ur 145 1.5 1 5 15 1 5 1 5 Ethylidene aniline. 2 2 Tnrnene 2 2 Hexamethylenetetramine 3 3 Cured in slab mold at 50 lbs. (148 0.) for time indicated 5 minutes 10 minutes Formula 15 Minutes 30 Minutes Undercure 560 1030 850 880 1140 925 sulfur-bearing organic accelerator, and vul-.

canizing the resulting mixture at a temperature not in excess of about 160 C.

3. The method of vulcanizin g rubber which comprises incorporating with the rubber a small percentage of sulfur not in excess of about 2% of the rubber, a small percentage of tellurium not in excess of about 2% of the rubber, and a small percentage of an organic accelerator, and vulcanizing the resulting mixture at a temperature not in excess of about 160 C.

4. As a new product, vulcanized rubber, characterized by the addition thereto be 5. The method of vulcanizing rubber which comprises incorporating with the rubber a small percentage of crystalline sulphur, a

small percentage of elemental tellurium not in excess of about two per centof the rubber,

60 Minutes e10 870 980 860 so 1770 880 130 2080 860 and a small amount of an organic accelerator I and vulcanizing the resulting mixture at a temperature not in excess of 160 C.

6. The methodof vulcanizing rubber which comprises incorporating with the rubber a mixture at a temperature not in excess of about 160 C.

7. The method of vulcanizing rubber which comprises incorporating with the rubber a small percentage of crystalline sulphur not in excess of about two per cent of the rubber,

a small percentage of elemental tellurium not in excess of about two per cent of the rubber,-and a small percentage of an organic accelerator and vulcanizing the resulting mixture at a temperature not in excess of 160 C.

8. The method of vulcanizing rubber which comprises incorporating with'the rubber a small percentageof crystalline sulphur, a small percentage of elemental tellurium and a small percentage of a tetra-alkyl-thiurem disulfide and vulcanizing the resulting mixture at a temperature not in excess of about 160 C. e i

9. The method of vulcanizing rubber which comprises incorporating with the rubber a small percentage of crystalline sulphur, a small percentage of elemental tellurium and a small percentage of mercapto-benzol-thiazole and vulcanizing the resulting mixture at a temperature not in excess of 160 C.

10. As a new product, vulcanized rubber which is characterized by its good aging qualities and further characterized by the addition thereto before vulcanization of a small percentage of sulphur, a small percentage of ,tellurium and a small percentage of a tetra-alkyl-thiuramrdisulfide, such product being vulcanized at a temperature not in excess of about 160 C..

11. As a new product, vulcanized rubber characterized by its good aging qualities and further characterized by the addition thereto before vulcanization of a small percentage of sulphur, a small percentage of tellurium and a small percentage of mercapto-benzol-v thiazole, such product being vulcanized at a temperature not in excess'of C.

In testimony LAURENCE A. EDLAND.

whereof I afiix my signature. l 

